1. Field of Invention
The present disclosure relates to a method for using a tubular string to detach a downhole tool from a wellbore wall. More specifically, the present disclosure concerns a method of disconnecting a wireline from a downhole tool that is stuck in a wellbore, connecting a tubular string to the downhole tool, and using the string to unstick the tool from the wall and continue wellbore operations after unsticking the tool.
2. Description of Prior Art
Tools for use in a wellbore that are typically deployed on a wireline include perforating guns, nuclear imaging tools, seismic imaging tools, resistivity tools, and casing collar locators. The wireline connects to the tool via a cablehead, which is generally on the uppermost portion of the particular tool. Cableheads generally include some form of electrical connection for providing signal and/or electrical communication between the wireline and the tool.
As the wireline is a generally pliable member, wireline tools typically rely on gravity to be lowered downhole. While tractors are sometimes relied on to pull wireline tools through horizontal sections of a wellbore; tractors are usually not used unless the wellbore has highly deviated portions. Wireline tool sometimes become stuck downhole because of debris deposits between the tool and sidewalls of the wellbore, pressure differentials between the wellbore and formation, or mired in the mudcake that lines the wellbore walls. Other examples of being stuck include when the tool encounters a packed off area in the wellbore, or some other restriction. Because the force required to dislodge the downhole tool often exceeds the tensile strength of the wireline, intervention is typically required to continue wellbore operations.
Intervention to unstick a wireline deployed downhole tool is usually performed by disconnecting the wireline from the tool, and “fishing” the stuck tool from the wellbore by attaching a string of drill pipe to the downhole tool, such as with an overshot tool. After the drill pipe is coupled to the downhole tool, an axial force is applied to the string, which transfers to the attached downhole tool to overcome the sticking force. To anticipate a stuck situation, frangible links are included in most cableheads that are designed to fracture under tension before the wireline fails. Fishing operations are more difficult if an amount of wireline remains in the wellbore prior to inserting the drill pipe.